( 476 ) 



The two first lines of' R.S. Q;iye a difFerentinl vihi-ation 



140391 



(2.B.S.) — (1.B.S.) =3 2470,42 ;./, = 40480 4,06 ft (Moll). 40449 (P.j 



(40572 



(The calciihiti'd line.-; give the freqiieney (liHerenfe 2465,6 and 

 h = 40558). 



Moll's line 2,90ft is probably a differential vibration: 

 (1,1 S.S.) — (IJIS.S.) = 3432,37, h = 29135. 



Potassium. In this element and the following Rb. and Cs. with 

 greater atomic weight a differential series formed from the principal 

 series has not been observed. With increasing atomic weight the 

 intensity of the principal vibrations does not seem great enough at 

 the temperature used to give rise to differential vibrations of sufficient 

 intensity to be observed. At any i-ate the circumstances of their 

 formation seem to be such that their energy is distributed over 

 combinations with tlie first lines of the subordinate series; such 

 combinations namely, have in fact been observed. (Jalculation gives 

 for K. as first doublet of a dilferential sej-ies : 



8561 and 8533 ; 6262 and 6242,9. 



Paschen gives as first doublet of the I S.S. 11689.8 and 11771,7. 

 The first lines of the (calculated) differential series give differential 

 vibrations with the first lines of tlie subordinate series. 



(1,D.S.) -(1,1 S.S.) =3164,9 ;^ = 31598 '<. =31596,8(P. 4) . 



(1,D.S.) -(1,1 S.S.) =3186,2 .^=31381 /,, =31395 (p. 5) s ^.^^ I^ollj 



(2,IS.S.) -(1,D.S.) = ? 1)', ? '.•=3-?075,6(P.3) , 



(2, 1 S. S.) - (1 , D. S.) = 2676 '0 = 37369 /,, = 37370,7 (P. 5) ) ^' '^ ^^^"^^^^ 



(3,1S.S.) -(1,D.S.) =5484,9 ., = 18232 i ^^, ^^^^^^^^ 



(3,IS.S.) -(1,D.S.) =5465,1 /, = 18298 ) not oDservea 



(1, D. S.) - (1, II S. S.) = 3695,5 /, = 27060 .,„ = 27065,6 (P. D . . -. .„^, , . 



(l.D.S.) —(1,11 S.S.) =3677,0 ',=27197 ^^,=27215 (p. 2) ^ ^' "^ ^'"^^lj 



(2, II S.S.) - (1, D. S.) = 2730,7 '■, = 36621 /,„ = 36614,3 (P. 4) 



(2, II S. S.) — (1, D. S.) = 2750,0 ., = 36364.2/,,, = 36372,7 (P. 4) 



(3, II S.S.) -(l.D.S.) =5554,4 '6=18003.7, 



(3, II S.S.) - (1, D. S.) = 5573,8 ., = 17941 .3 S "°^ oobervca 



(2, D. S.) - (1, 1 S. S.) = 7464 ., = 13398 , 



(2,D.S.) -(1,1 S.S.) =7474,9 /, = 13378 ^ "oi oDseivea 



(2,D.S.) -(2,IS.S.) = ? /, ? .,,= 6. 236. (P.) 



(2, D.S.) —(2, 1 S.S.) =1612,7 /, =62010 ^ ,. = 6.203 y (P.) 



(3, 1 S.S.) —(2, D.S.) =1185,8 /, = 84332 /,,. = 8.452 /. (P.) 



(3, 1 S.S.) -(2D. S.) =1176,4 /,= 85004 ^ = 8.510,^ (P.) 



ij Of the 2°*^ doublet of Uie I S.S. a = 6964,4 n = 14357 has been observed 

 by RiTZ. This value seems better than Saunders's G966,3. The other component 

 has not been observed; it can be fomid hOni the combination by recalculation. 

 It lies in the immediate neighbourhood of 6938,8 (2. II, S.S.). 



